Tracking a star over time
I have a question.
Is there a way to calculate the altitude and azimuth of a star at a given time using as an input the altitude and azimuth of that star at an earlier time, without having to convert those coordinates to RA and DEC?
The problem is that I want to calculate the position (alt,az) of a nine stars a a later time when I know where the stars are right now. I don' want to calculate the RA and DEC of each star and then calculate back. I hope that there might a formula but I haven't found it yet.
Thank you for your help